KR20000044177A - Projection type image display device - Google Patents

Abstract

PURPOSE: A projection type image display device is provided to embody an optical system of high efficiency using two optical modulators and enhance the uniformity of illumination to remove shimmering phenomenon. CONSTITUTION: A projection type image display device comprises a light source(102), a color filter(104), a hybrid prism(108) and a projection lens(124). The color filter(104) divides light from the light source(102) into a forth color beam, a fifth color beam and a first color beam. The forth color beam is formed by combining the first color beam and a second color beam. The hybrid prism(108) has first to third surfaces(110,112,114). The first surface(110) generates uniform beam. First and second dichroic filters(116,118) for respectively transmitting the second/third color beams and the first beams are attached to the second surface(112). First and second optical modulators(120,122) are attached to the third surface(114). The color beams passing through the prism(108) are projected to a screen by the projection lens(124).

Description

Projection type image display device

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a projection image display device, and more particularly, to a projection image display device capable of improving illumination uniformity, effectively eliminating shimmering, and implementing a highly efficient optical system using two optical modulators. It is about.

Optical path control devices or spatial light modulators for projecting optical energy onto the screen can be applied to various fields such as optical communication, image processing and information display devices. Typically, image processing apparatuses using such an optical modulator are classified into a direct view type image display device and a projection type image display device according to a method of displaying optical energy on a screen.

An example of a direct view image display device is a CRT (Cathode Ray Tube), which is a so-called CRT device, which has excellent image quality but increases in weight and volume as the size of the screen increases, leading to increased manufacturing costs. There is. Projection type image display apparatuses include liquid crystal display (LCD), Deformable Mirror Device (DMD) and Actuated Mirror Array (AMA). Such projection image display apparatuses can be further divided into two groups according to their optical characteristics. That is, devices such as LCDs can be classified as transmission light modulators, while DMD and AMA can be classified as reflective light modulators.

Transmission optical modulators, such as LCDs, have a very simple optical structure, which makes them thinner, lighter in weight, and smaller in volume. However, the light efficiency is low due to the polarity of the light, there is a problem inherent in the liquid crystal material, for example, the response speed is slow and its inside is easy to overheat. In addition, the maximum light efficiency of existing transmission optical modulators is limited to a range of 1-2% and requires dark room conditions to provide acceptable display quality. Therefore, optical modulators such as DMD and AMA have been developed to solve the above problems.

Although DMD shows a relatively good light efficiency of about 5%, the hinge structure employed in the DMD not only causes serious fatigue problems, but also requires a very complicated and expensive driving circuit.

The AMA reflects the light incident from the light source at a predetermined angle, and each mirror installed therein adjusts the luminous flux so that the reflected light is projected on the screen through an opening such as a slit or pinhole to form an image. Device. Therefore, its structure and operation principle are simple, and high light efficiency (more than 10% light efficiency) can be obtained compared to LCD or DMD. In addition, the contrast of the image projected on the screen is improved to obtain a brighter and clearer image.

Each actuator of the AMA generates a deformation in accordance with the electric field generated by the applied electric image signal and the bias voltage. As the actuator deforms, each of the mirrors mounted thereon is tilted. Therefore, the inclined mirrors reflect the light incident from the light source at a predetermined angle to form an image on the screen. As an actuator for driving the respective mirrors, a piezoelectric material such as PZT (Pb (Zr, Ti) O ₃ ), or PLZT ((Pb, La) (Zr, Ti) O ₃ ) is used. It is also possible to configure the actuator as electrostrictive material such as PMN (Pb (Mg, Nb) O 3).

These AMAs are classified into bulk and thin film types. Bulk AMA is disclosed in US Pat. No. 5,085,497 to Gregory Um et al. The bulk AMA is made by thinly cutting a multilayer ceramic to mount a ceramic wafer having a metal electrode formed therein in an active matrix in which a transistor is built, and then processing by a sawing method and installing a mirror on the top. However, bulk AMA requires very high precision in design and manufacture, and has a disadvantage of slow response of the strained layer. Accordingly, recently, a thin film type AMA (TMA) that can be manufactured using a semiconductor manufacturing process has been developed. For example, such a TMA is disclosed in Korean Patent Application No. 95-13353 (name of the invention: a method for manufacturing an optical path control device) filed by the applicant with the Korean Patent Office.

TMA is a reflective optical modulator using thin film piezoelectric actuators in connection with microscopic mirrors, and has been developed to have uniformity of large scale integration over more than 300,000 pixels of a single plate mirror. This TMA consists of panels of 640x480 pixels representing red (R), green (G), and blue (B), respectively. The pixels are designed as cantilever structures to maximize the surface area of the mirror to increase light efficiency. The cantilever structure includes an active matrix to which an image signal voltage is applied and a mirror operated by the applied signal voltage.

Fig. 1 shows a projection type image display apparatus capable of displaying color images using a three panel TMA.

Referring to FIG. 1, a conventional projection type image display apparatus 10 includes 170W to 250W halogen metal lamps 11 for emitting light rays, and source lenses 12 for making light rays emitted from the lamps 11 into parallel light. ), A source stop 13 having an opening for passing the light beam and determining an amount of the light beam forming an image, a source mirror 14 for primarily changing the path of the light beam passing through the source stop 13, Two dichroic filters 17 and 18 for selectively passing light by wavelength and three fields for 1: 1 correspondence of the phase of the source stop 13 to the projection stop 15. Three TMA panels 20, 22, and 24, which consist of an array of mirror pixels 30, 32, and 34, for modulating the intensity of the light emitted from the field lenses 30, 32, and 34, passing through the rays. Focusing flux of modulated rays A projection stop 15 for turning on, and a projection lens 16 for projecting a light beam passing through the projection stop 15 onto a screen (not shown).

The operation principle of the conventional projection type image display apparatus 10 having the above-described structure will be described as follows.

Light rays generated from the lamp 11 are made into parallel light in the source lens 12 and then irradiated on the source mirror 14 through the opening of the source stop 13. The light rays irradiated on the source mirror 14 are totally reflected and irradiated on the first dichroic filter 17.

Since the first dichroic filter 17 transmits green light and blue light and reflects red light, the reflected red light is irradiated to the R-TMA 20 through the R-field lens 30. The mirror of the R-TMA 20 modulates the light beam in accordance with a signal applied to an actuator provided thereunder. As a result, the red light modulated by the R-TMA 20 is irradiated back to the first dichroic filter 17 through the R-field lens 30 and then reflected by it to the projection stop 15. . The red light passing through the opening of the projection stop 15 is incident on the projection lens 16.

On the other hand, green light and blue light transmitted through the first dichroic filter 17 are reflected by the second dichroic filter 18 and blue light is transmitted. The blue light reflected by the second dichroic filter 18 is irradiated to the B-TMA 22 through the B-field lens 32. The mirror of the B-TMA 22 modulates the light beam in accordance with a signal applied to an actuator provided thereunder. As a result, the blue light modulated by the B-TMA 22 is irradiated back to the second dichroic filter 18 through the B-field lens 32, and is reflected therefrom to reflect the first dichroic filter 17. Is investigated. Since the first dichroic filter 17 transmits blue light as it is, the transmitted blue light passes through the opening of the projection stop 15 and then enters the projection lens 16.

Green light transmitted through the second dichroic filter 18 is irradiated to the G-TMA 24 through the G-field lens 34. The mirror of the G-TMA 24 modulates the light beam in accordance with a signal applied to an actuator provided thereunder. As a result, the green light modulated by the G-TMA 24 is irradiated back to the second dichroic filter 18 through the G-field lens 34, and passes through the second dichroic filter 18. Irradiated with the first dichroic filter 17. Since the first dichroic filter 17 transmits green light as it is, the transmitted green light passes through the opening of the projection stop 15 and then enters the projection lens 16.

In this way, the projection lens 16 projects a color ray including three rays of red, green and blue on the screen to display a color image corresponding thereto.

According to the conventional projection type image display apparatus described above, since three TMA panels are used, manufacturing costs are high and the size of the optical system is increased. In addition, when a high output lamp is used to improve the brightness of the screen, not only the uniformity of illumination is lowered but also a so-called shimming phenomenon occurs in which a shaking image such as a haze appears on the screen.

Accordingly, it is an object of the present invention to provide a projection type image display apparatus that can implement an optical system of high efficiency, improve illumination uniformity, and effectively eliminate the shimmering phenomenon by using two light modulators.

1 is a schematic diagram showing a conventional projection type image display apparatus.

Fig. 2 is a schematic diagram showing a projection image display apparatus according to the present invention.

3 is a plan view of a color wheel used in the apparatus of FIG.

4 is a schematic diagram illustrating a propagation path of green and blue light rays in the apparatus of FIG. 2.

FIG. 5 is a schematic diagram for explaining a propagation path of red light in the apparatus of FIG. 2. FIG.

<Description of the symbols for the main parts of the drawings>

100: projection image display device 102: light source

104: color wheel 106: condenser lens

108: hybrid prism 116, 118: dichroic filter

120, 122: reflective optical modulator 124: projection lens

In order to achieve the above object, the present invention provides a light source for emitting a light beam, and the first color light beam and the second color light beam are included in three primary colors of light including the first, second, and third color light rays. A fourth wheel combined with a first color beam and a fifth wheel combined with the first and third color beams, a color wheel for separating the first color beam, a first surface for making the light beam uniform, a fourth surface obtained from the color wheel, and A second side, second and third color with a first dichroic filter for transmitting the second and third color light rays from the fifth color light and a second dichroic filter for transmitting the first color light A hybrid prism having a third surface to which a first reflective light modulator for modulating a light beam and a second reflective light modulator for modulating a first color light are attached, and color rays passing through the hybrid prism For projecting on screen Provided is a projection image display device having a projection lens.

As described above, in the present invention, a plurality of prisms are connected to each other, and a dichroic filter and a reflective optical modulator are attached to each surface of the prism thus obtained, so that the other components of the optical system except for the light source are prism. Color separation and synthesis are performed by using a hybrid prism integrated into the optical sensor, and two highly reflective optical modulators can be used to implement an optical system having high efficiency. In addition, by forming one side of the hybrid prism in the form of a light pipe, it is possible to improve the uniformity of illumination and effectively eliminate the shimmering phenomenon.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

Fig. 2 is a schematic diagram showing a projection image display apparatus according to the present invention.

Referring to FIG. 2, the projection image display apparatus 100 of the present invention includes a light source 102, a color wheel 104, a condenser lens 106, a hybrid prism 108, and a projection lens 124.

The light source 102 for emitting light is preferably a kW-class halogen metal lamp, and in order to improve the brightness of the screen, it is necessary to generate light rays having a large amount of light to form pixels, and thus use a lamp of high power as possible.

The color wheel 104 includes a fourth color light beam of which the first color light beam and the second color light beam are combined among the three primary colors of the light emitted from the lamp 102, the first, second and third color light beams; It serves to continuously separate into the first color light and the fifth color light and the first color light and the third color light.

3 is an enlarged plan view of the color wheel 104.

Referring to FIG. 3, a color wheel 104 according to a preferred embodiment of the present invention is a transmission filter of yellow light Y in which red light R and green light G are combined, and a red light R and blue light. (B) consists of a series of color fragments of the transmission filter of magenta light M combined, and changes the color of the white light while rotating about its axis by a driving device such as a motor. Thus, the color wheel 104 continuously separates the white light emitted from the lamp 102 into red light (R), yellow light (Y) and magenta light (M).

The condenser lens 106 serves to make the colored light obtained by the color wheel 104 into parallel light.

The hybrid prism 108 is preferably formed by connecting three prisms to each other and attaching a dichroic filter and a reflective light modulator to each side of the prism thus obtained. That is, the hybrid prism 108 is used to transmit the second color light and the third color light from the first surface 110 to make the light beam uniform, and the fourth and fifth color light rays obtained from the color wheel 104. A second face 112 to which the first dichroic filter 116 and the second dichroic filter 118 are attached, for transmitting the first color light, and the second and third color light modulating agents. And a third surface 114 to which the first reflective light modulator 120 and the second reflective light modulator 122 for modulating the first color light ray are attached.

Preferably, the first face 110 of the hybrid prism 108 is an optical integrated surface in the form of a light pipe and properly mixes the light rays emitted from the lamp 102 to adjust its intensity and angle. It makes it even and removes the shimmering phenomenon. Light pipes are light transmission elements that use unfocused transmission or reflection to reduce light loss and are used to distribute light more evenly. Specifically, the light pipe may be used to pre-cut the loss of the circular beam to prevent the loss of part of the circular beam when the circular beam emitted from the lamp passes through the optical component, such as a stop or lens. It acts as a scrambler to redistribute the angular distribution of light using the total reflection surface, and to reduce the color shift caused by the reflector located at the rear of the lamp.

Preferably, the first dichroic filter 116 attached to the second surface of the hybrid prism 108 transmits the green light G and the blue light B, reflects the red light R, and the second dichroic light. The blade filter 118 transmits the red light R and reflects the green light G and the blue light B.

Reflective light modulators 120 and 122 are preferably TMA panels consisting of an array of mirrors for reflecting light rays. Each mirror of the TMA panels 120 and 122 modulates the intensity of the light beam in accordance with a signal applied to an actuator formed thereunder. That is, each mirror is deformed to a deformation size corresponding to the intensity of the corresponding one pixel among the plurality of pixels displayed on the screen. According to a preferred embodiment of the present invention, the first TMA panel 120 is continuously irradiated with green light (G) and blue light (B) transmitted through the first dichroic filter 116, and the second TMA panel 122 ) Is irradiated with red light R transmitted through the second dichroic filter 118.

Below. The operation principle of the projection image display apparatus 100 according to the present invention having the above-described structure will be described with reference to FIGS. 2 to 5.

4 is a schematic diagram for explaining a propagation path of green (G) and blue (B) rays in the projection type image display device 100 of the present invention, and FIG. 5 is a diagram for explaining the propagation path of a red ray R. FIG. Schematic diagram.

First, the white light emitted from the lamp 102 is focused on the color wheel 104, and the color wheel 104 rotates about its axis while the yellow light (Y) in which the white light (R) and the green light (G) are combined. The red light R and the blue light B are successively separated into magenta light M and red light R. The red light R, the yellow light Y, and the magenta light M thus separated are made into parallel light by the condenser lens 106 and incident on the hybrid prism 108.

Yellow light Y entering the hybrid prism 108 is reflected from the first surface 110 of the hybrid prism 108 and irradiated to the first dichroic filter 114 attached to the second surface 112. Since the first dichroic filter 114 is a filter for transmitting green light (G) and blue light (B) and reflecting red light (R), the green light (G) is transmitted from the yellow light (Y) to hybrid prism (108). Is irradiated to the first TMA panel 120 attached to the third side 114 of the substrate. Each mirror of the first TMA panel 120 modulates the green light G in accordance with a green image signal applied to an actuator provided thereunder. As a result, the green light G modulated by the first TMA panel 120 passes through the first dichroic filter 114 and is reflected from the first surface 110 of the hybrid prism 108, and then The second dichroic filter 118 attached to the second surface 116 is irradiated. Since the second dichroic filter 118 transmits the red light R and reflects the green light G and the blue light B, the green light G reflected from the second dichroic filter 118 is a hybrid prism ( Passed through 108 is incident on the projection lens 124.

The red light R entering the hybrid prism 108 is reflected from the first surface 110 and irradiated to the first dichroic filter 114 attached to the second surface 112. Since the first dichroic filter 114 is a filter that transmits the green light G and the blue light B and reflects the red light R, the red light R reflected from the first dichroic filter 114 is a hybrid. The second dichroic filter 118 attached to the second face 116 after being reflected from the first face 110 of the prism 108 is irradiated. Since the second dichroic filter 118 transmits the red light R and reflects the green light G and the blue light B, the transmitted red light R is transmitted to the third surface 114 of the hybrid prism 108. The attached second TMA panel 122 is irradiated. Each mirror of the second TMA panel 122 modulates the red light R in accordance with a red image signal applied to an actuator provided thereunder. As a result, the red light R modulated by the second TMA panel 122 passes through the second dichroic filter 118 again, passes through the hybrid prism 108, and then enters the projection lens 124.

Magenta light M entering the hybrid prism 108 is reflected from the first surface 110 of the hybrid prism 108 and irradiated to the first dichroic filter 114 attached to the second surface 112. Since the first dichroic filter 114 is a filter that transmits green light (G) and blue light (B) and reflects red light (R), the blue light (B) is transmitted from the magenta light (M) to allow the hybrid prism (108). Is irradiated to the first TMA panel 120 attached to the third side 114 of the substrate. Each mirror of the first TMA panel 120 modulates the blue light B in accordance with a blue image signal applied to an actuator provided thereunder. As a result, the blue light B modulated by the first TMA panel 120 passes through the first dichroic filter 114 and is reflected from the first surface 110 of the hybrid prism 108, and then The second dichroic filter 116 attached to the second surface 116 is irradiated. Since the second dichroic filter 116 transmits the red light R and reflects the green light G and the blue light B, the blue light B reflected from the second dichroic filter 116 is a hybrid prism ( Passed through 108 is incident on the projection lens 124.

In this way, the projection lens 124 projects a color ray including three rays of red, green and blue on the screen to display a color image corresponding thereto. Preferably, the color image is implemented by a time sharing scheme. For example, the yellow light Y obtained from the color wheel 104 is projected on the screen in a green image and a red image by the first TMA panel 120 and the second TMA panel 122 for 1/2 second, When the magenta light M obtained from the color wheel 104 continuously is projected on the screen in a blue image and a red image by the first TMA panel 120 and the second TMA panel 122 for 1/2 second, the naked eye The red, green, and blue images are combined together to be recognized as white images. Thus, in this manner, each of the monochrome images can be combined to realize all colors.

As described above, according to the projection type image display apparatus of the present invention, a plurality of prisms are connected to each other, and a dichroic filter, a reflection type optical modulator, and the like are attached to each surface of the prism thus obtained, whereby a light source is used. High efficiency optical system can be realized by performing color separation and synthesis using a hybrid prism integrating components other than the prism and using two reflective optical modulators. In addition, by forming one side of the hybrid prism in the form of a light pipe, it is possible to improve the uniformity of illumination and effectively eliminate the shimmering phenomenon.

Although the above has been described with reference to a preferred embodiment of the present invention, those skilled in the art will be variously modified and changed within the scope of the invention without departing from the spirit and scope of the invention described in the claims below. I can understand that you can.

Claims (3)

A light source 102 for emitting light rays; A fourth color light beam of which the first color light beam and the second color light beam are combined among the three primary colors of light including the first, second, and third color light beams emitted from the light source 102, and the first color light beam A color wheel 104 for separating the fifth color light with the third color light and the first color light; Iii) a first side 110 for making the light beam uniform, ii) a first dichroic for transmitting the second and third color light rays from the fourth and fifth color light rays obtained from the color wheel 104. A second surface 112 to which a filter 116 and a second dichroic filter 118 are attached for transmitting the first color light and iii) a first reflection for modulating the second and third color light A hybrid prism (108) having a fluorescent modulator (120) and a third surface (114) attached with a second reflective optical modulator (122) for modulating said first color light beam; And And a projection lens (124) for projecting the colored light rays passing through the hybrid prism (108) onto the screen. The projection image display apparatus according to claim 1, wherein the first and second reflective optical modulators (120, 122) are thin-film mirror array panels. The projection type image according to claim 1, wherein the first color light is red light, the fourth color light is yellow light in which red light and green light are combined, and the fifth color light is magenta light in which red light and blue light are combined. Display device.